1. Priority Claim
This is the national phase application of PCT Application No. PCT/EP01/12515 filed on Oct. 30, 2001.
2. Field of the Invention
The invention relates to a clutch system including at least one clutch device, particularly for arrangement in a drivetrain (especially in a motor vehicle) between a drive unit and a transmission, wherein the clutch device has at least one clutch arrangement which is provided for operation under the effect of an operating medium and/or which can be actuated through a pressure medium.
3. Description of the Related Art
Reference is made herein in particular, but not exclusively, to a wet multi-disk clutch arrangement. Further, reference is made herein above all, but not exclusively, to a clutch arrangement which can be actuated by hydraulic means with a hydraulic slave cylinder integrated in the clutch device as is disclosed, for example, in U.S. Pat. No. 5,887,690 or in one of the present Assignee's patent publications concerning multiple clutch devices (particularly dual clutch devices). Reference is made particularly to U.S. Pat. Nos. 6,499,578, 6,523,657, and 6,586,852. The clutch arrangements of the referenced clutch devices are wet multi-disk clutch arrangements. U.S. Pat. No. 6,059,682 can be referred to with respect to wet, hydraulically actuated multi-disk clutch arrangements. A dry hydraulically actuated dual clutch device is known from U.S. Pat. No. 4,714,147.
In principle, there are many possible ways in which an operating medium, possibly a cooling liquid (especially cooling oil), is supplied to the clutch arrangement or to a plurality of clutch arrangements of the clutch device. It is the job of the designer to keep the costs and space requirement as low as possible while providing for a good efficiency and, accordingly, a low energy consumption for supplying the operating medium.
In some cases, other marginal conditions must be accounted for as well. For a clutch device with one or more wet, hydraulically actuated clutch arrangements (particularly multi-disk clutch arrangements), a flow of hydraulic medium must be supplied for controlling the clutch device or clutch devices in order to activate a clutch, i.e. engage a normally open type clutch or disengage a normally closed type clutch. A relatively small volume flow at relatively high pressure is needed for engaging and disengaging. Further, a large volume flow of coolant, particularly cooling liquid (generally oil), is required for wet operation or for cooling of the clutch devices, wherein a volume flow at a lower pressure level is sufficient or even necessary.
It is possible to provide two separate pumps which are driven by motor (e.g., determined by the drive unit and/or transmission) or by electric motor, one of which is designed to supply the pressure medium flow for controlling the clutch device or clutch devices and the other is designed for supplying the flow of operating medium. However, this solution is comparatively costly.
DE 198 00 490 A1 discloses another approach. A suction jet pump is provided in the supply area of a hydraulic fluid serving to cool a multi-disk clutch arrangement in order to achieve high throughflow rates and, therefore, a high cooling output. The suction jet pump receives a flow of hydraulic fluid from a hydraulic pump which provides a hydraulic pressure sufficient for actuating the multi-disk clutch arrangement. The suction jet pump sucks additional hydraulic fluid out of the oil pan.
While the hydraulic pump need not be designed for very high pumping outputs and a separate motor-driven pump for pumping coolant can be dispensed with using the approach disclosed in DE 198 00 490 A1, the approach based on the suction jet pump is disadvantageous because the efficiency of the suction jet pump is comparatively poor due to the high vortex losses of a suction jet pump and the energy consumption is consequently relatively high.